Many telephone callers must place calls from noisy environments. For example, travelers must often use pay phones or wireless terminals from locations such as airports or train stations, for example, that suffer from high ambient noise levels. The ambient noise at such locations often over powers the caller's speech, causing the telephone set to transmit noise rather than intelligible speech to the called party. The noise received from a caller originating a call from a noisy location is especially irritating during a conference call when the caller is but one of many participants.
Presently, various techniques exist to address the problem of ambient noise interfering with a caller's speech for calls originated from noisy locations. For example, AT&T now employs speech-processing equipment within its telecommunications network to filter callers' speech to reduce the effect of ambient noise. While such speech processing equipment is generally effective, high levels of ambient noise can defeat such filtering. Rather than utilize complex filtering techniques, subscribers who have telephone sets that offer a mute feature can self-mute their outgoing speech. Unfortunately, not all pay phones or wireless terminals offer muting capability so that a subscriber seeking to mute his or her speech must manually cover the terminal microphone, often at great inconvenience. Moreover, even if a calling party has a mute feature on his or her telephone, the caller may not know that the level of background noise is so excessive as to interfere with the caller's speech.
In connection with conference calls, U.S. patent application Ser. No. 09/133,118, filed Aug. 12, 1998 in the name of Brian Brown et al., and assigned to AT&T, discloses a technique for enabling a first conference call participant to selectively mute other participants to the conference call. In this way, two or more participants can conduct a private conversation to the exclusion of all others. While the muting technique taught by Brown et al. affords the opportunity to mute individual callers, the technique does so only in connection with a conference call, rather than a conventional two-party call. Moreover, the muting technique of Brown et al. mutes both the incoming and outgoing speech of participants. Thus, Brown et al. provides no mechanism to allow a caller to self-mute only outgoing speech, nor does Brown et al. accomplish automatic muting of only outgoing speech in response to a high noise level.
Thus, there is need for a technique for enabling a caller to self-mute outgoing speech while still receiving speech from a called party.